1. Field of the Invention
The present invention relates to document processors which read indicia on documents as the documents move from an input hopper toward a plurality of pockets, then sort each document into one of the pockets based on the indicia read. The present invention relates to improved control of the feeding of documents to achieve increased throughput.
2. Prior Art
Document processing machinery designs have a dilemma in that on one hand, high speed movement of the documents is desirable, but, on the other hand, the equipment has limitations in how fast it can operate. For example, the electromechanical gates which open and close to direct one document into a selected pocket, can only operate so quickly within the interdocument gap. If the documents are fed at a higher rate, a shortened gap will result causing errors to occur, such as improper sorting or failure to sort.
Increasing document transport speed will increase document gap but can result in document damage as well as processing and stacker errors.
Further complicating the design is that components involved with the feeding of documents rely on mechanical friction using components which wear and are influenced by environmental factors such as temperature and humidity.
One way to approach these design constraints is simply to choose an operating point which is sufficient to allow for wear and environmental concerns. While this can be effective, it implies some sacrifice of potential performance.
Another way to compensate for such variable factors is to attempt to keep the gap between documents relatively constant.
Examples of such prior art systems include U.S. Pat. Nos. 4,451,027 and 4,331,328.
The referenced prior art is limited in performance by the inertia of the plurality of rollers accelerated. This means that a high amount of power may be required and excessive heat may be generated, both of which are undesirable.
Other limitations and disadvantages of prior art systems are apparent to those skilled in the art of document processor control systems.